JP3397401B2 - Imaging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly, to easily obtain high resolution image information by using a plurality of image pickup elements having a limited number of pixels without increasing the number of pixels of the image pickup element. In addition, the present invention relates to an image pickup apparatus which is capable of performing automatic focusing without image deterioration and is suitable for, for example, a small video camera or a still video camera.

[0002]

2. Description of the Related Art In recent years, solid-state area sensors (image sensors in which pixels are two-dimensionally arranged) as image pickup devices used in image pickup devices such as small video cameras and still video cameras have high pixel counts and low prices. It can be made smaller and smaller, and is used in many imaging devices.

The number of pixels of an image pickup device which is currently put into practical use is about 400,000, which has a resolution equivalent to that of a television of the current standard such as NTSC. However, for example, when the input image is displayed on a large screen image, hard copy or computer graphic,
The roughness of the pixels becomes noticeable, and it is difficult to output as a high-definition image.

Recently, a solid-state area sensor of 2 million pixels for HDTV is being developed. However,
Even with this number of pixels, the resolution is not sufficient to be used as an input for super-large screen display. The number of pixels of the current area sensor is not always sufficient to obtain an image with higher resolution (high resolution).

Conventionally, as a method of obtaining a high-definition image using an image pickup device, there is a method of obtaining a high-resolution image by increasing the pixel density of the image pickup device and increasing the number of pixels.

Generally, when the pixel area is reduced in order to increase the pixel density, the output signal becomes small and the S / N ratio deteriorates. Considering this decrease in the S / N ratio, the number of pixels of 2 million is almost the limit, and it is very difficult to further increase the number of pixels and improve the resolution under the present circumstances.

Therefore, various methods for obtaining a high-definition image without increasing the number of pixels have been proposed. For example, Japanese Patent Publication No. 50-13052 and Japanese Patent Publication No. 59-189.
No. 09, Japanese Patent Publication No. 59-43035, and the like propose a method using pixel shifting.

In this pixel shift method, an optical element for splitting a light beam based on a subject image on the image plane side of the image pickup optical system,
For example, by disposing a dichroic prism, a half mirror, or the like, and imaging the light beams divided by the optical element with a plurality of solid-state area sensors arranged by shifting the position by a half pitch of pixels or less, a high resolution image can be obtained. I'm getting an image.

Further, in Japanese Patent Laid-Open No. 4-286480, one or more optical path splitting means is arranged behind the imaging lens, the optical path splitting means divides the subject image into a plurality of divided subject images. An image is formed on each of a plurality of solid-state area sensor surfaces arranged at image forming plane positions, and the entire subject image is taken by interpolating areas that cannot be picked up by sensors at other image forming positions. Has obtained a high resolution image.

Further, in Japanese Patent Laid-Open No. 63-193678, a wedge-shaped deflecting member is arranged in the optical path of the photographing optical system, and the movement of the image caused by the rotation of the deflecting member is periodically picked up by an image pickup element. Therefore, image information of more than the number of pixels is obtained.

Further, in Japanese Patent Application Laid-Open No. 60-250789, a subject image formed by a photographing optical system is separated into a plurality of images by a secondary imaging optical system, and the separated plurality of images are respectively separated by a plurality of image pickup devices. A high-resolution image is obtained by forming an image on a surface and synthesizing and outputting image pickup signals from the plurality of image pickup elements.

[0012]

The method using pixel shifting as a method for obtaining a high-definition image has a problem that the resolution does not increase so much for the number of elements (pixels).

In the method proposed in Japanese Patent Laid-Open No. 4-286480, a high resolution image can be obtained by increasing the number of divisions of the optical path innumerably. For that purpose, the back focus of the taking lens is used. Had to be extremely long, and there was a problem that the size of the entire apparatus was increased. Therefore, in practice, the two-plate type or the three-plate type is the limit even if a 3P prism or the like is used.

Further, the method proposed in Japanese Patent Laid-Open No. 63-193678 is not suitable for a moving image because an image of one frame is combined by taking a plurality of times, and even if it is a still image, it is an output image. There was a problem that it took too much time to obtain.

Further, in the method proposed in Japanese Patent Laid-Open No. 60-250789, a light beam splitting mirror as a light beam splitting means is arranged so as to be slightly shifted from the primary image forming plane so that a boundary portion of an image is formed. Although pixel loss is prevented, there is a problem in that the structure is very difficult due to problems such as the thickness of the light beam separation mirror and the pupil of the off-axis light beam. In addition, the number of pixels increases at most about 2 to 3 times, which makes it difficult to obtain a high-resolution image.

According to the present invention, a plurality of image pickup devices having a limited number of pixels are used to appropriately set the arrangement of each image pickup device and each optical element that constitutes an image pickup system when a subject image is formed on each image pickup device. Accordingly, it is an object of the present invention to provide an image pickup apparatus capable of easily obtaining high-definition image information and performing automatic focusing without image deterioration.

[0017]

(1-a) The image pickup apparatus of the present invention forms a subject image on a predetermined image forming plane by the first optical system, and it is on the optical axis of the first optical system. And a second optical system disposed near the planned image plane and a third optical system disposed on the optical axis of the first optical system and behind the second optical system. All of the subject image formed on the image plane is re-imaged on the first image pickup means, has an optical axis outside the optical axis of the first optical system, and is arranged behind the second optical system. Image information obtained by the first imaging means and the second imaging means by re-imaging a part of the subject image formed on the planned imaging surface by the fourth optical system on the second imaging means. Is an image pickup apparatus that obtains high-definition image information by utilizing a signal from the first image pickup unit and at least a part of the third optical system configured by the drive unit. Lens is characterized in that, or the / and to the first imaging means to be movable along the optical axis.

In particular, the fourth optical system has a plurality of lens systems, the second image pickup means has a plurality of image pickup elements corresponding to the plurality of lens systems, and Four
The plurality of lens systems of the optical system of (1) form the object images of the respective areas when the object image formed by the first optical system is divided into a plurality of areas on the corresponding image pickup device surfaces. Obtaining one image information by using image information obtained from a plurality of image pickup devices constituting the second image pickup means and image information obtained from the first image pickup means,
The third optical system and the plurality of lens systems of the fourth optical system are characterized by different imaging magnifications.

(1-b) In the image pickup device of the present invention, a subject image is formed on a predetermined image forming surface by the first optical system, and the first optical system and the optical axis arranged near the predetermined image forming surface. Is formed on the planned image plane by a second optical system and a third optical system arranged behind the second optical system and having the optical axes aligned with the first optical system. All of the subject image is formed on the surface of the first image pickup means, and a plurality of regions obtained by dividing the subject image formed on the planned image forming plane are divided into optical axes different from the optical axis of the first optical system. The plurality of image pickup element surfaces of the second image pickup means having a plurality of image pickup elements corresponding to the plurality of lens systems by the fourth optical system having a plurality of lens systems and arranged behind the second optical system. Each image is formed on the upper side, and the image information from the plurality of image pickup devices is combined to obtain the image information about the entire subject image. An image device, in which at least a part of the lenses forming the third optical system is driven by the driving means by using the signal from the first imaging means, and / or the first imaging means is on the optical axis. The feature is that it can be moved.

In particular, the plurality of lens systems of the third optical system and the fourth optical system are characterized by different imaging magnifications.

[0021]

FIG. 1 is a sectional view of the essential parts of an optical system according to the first embodiment of the present invention, and FIG. 2 is a perspective view of the essential parts of the first embodiment of the present invention.

In the figure, reference numeral 1 denotes a first optical system, which forms a subject image on a primary image forming surface (planned image forming surface) 21.

Reference numeral 2 is a second optical system, and the first optical system 1
Of the subject image formed on the primary image forming surface 21 and is guided to the subsequent lens system. There is.

Reference numeral 3 is a third optical system, and the first optical system 1
It is arranged on the optical axis of, and behind the second optical system 2 (on the image plane side). That is, the optical axis of the third optical system 3, the optical axis of the first optical system 1, and the optical axis of the second optical system 2 coincide with each other. The third optical system 3 is configured such that at least a part of the lenses constituting the third optical system 3 can be moved on the optical axis by a driving unit 33 described later.

Reference numeral 31 denotes a first image pickup means (main image pickup means), which is arranged on the image forming surface behind the third optical system 3 and is composed of, for example, a solid area sensor. The first image pickup means 31 is configured to be movable on the optical axis by a driving means 33 described later.

The entire area of the subject image formed on the primary imaging surface 21 by the first optical system 1 is recombined on the surface of the first image pickup means 31 by the second optical system 2 and the third optical system 3. I'm making you image.

The driving means 33 is composed of, for example, a piezoelectric element, and based on an output signal from the first image pickup means 31, at least a part of lenses constituting the third optical system 3 and / or the first lens. The image pickup means 31 is moved on the optical axis.

Reference numeral 4 denotes a fourth optical system, which has four lens systems: a 41st lens system 4A, a 42nd lens system 4B, a 43rd lens system 4C, and a 44th lens system 4D.

The four lens systems 4A, 4B, 4C and 4D have an optical axis outside the optical axis of the first optical system 1 and the second optical system 2
It is located behind.

Reference numeral 41 denotes a second image pickup means (sub-image pickup means), which is, for example, four image pickup elements 4 each including a solid-state area sensor.
1A, 41B, 41C, 41D, which are arranged on the image planes of the four lens systems 4A, 4B, 4C, 4D, respectively.

The four lens systems of the fourth optical system 4 (4A,
4B, 4C, 4D) divides the subject image on the primary image forming surface 21 formed by the first optical system 1 into a plurality of regions, and the subject images in the respective regions are respectively associated with image pickup devices 41A, 41B, 41.
The image is re-formed on the C and 41D planes.

In the second embodiment, in the second optical system 2, the pupil 1a of the first optical system 1 and the pupil 3a of the third optical system 3 are substantially conjugate with each other as shown by the optical path 32 of the solid line in the figure. I am trying. Further, as shown by an optical path 42 indicated by a broken line in the drawing, a plurality of lens systems 4A, 4B, 4C, 4D which constitute the fourth optical system 4 are formed.
The pupils 4A1, 4B1, 4C1 and 4D1 are imaged in the vicinity of the divided pupil regions of the first optical system 1, respectively.

Four lens systems (4A, 4B, 4C, 4D) of the third optical system 3 and the fourth optical system 4 in this embodiment.
The image forming magnifications of and are different from each other, which effectively aligns the pupil image formation.

In this embodiment, as shown in FIG.
The subject image is formed on the primary image forming surface 21 by the optical system 1, and the subject image is formed on the surface of the first image pickup means 31 by the third optical system 3 through the second optical system 2. The entire area of is imaged. Further, the four lens systems 4A, 4B, 4C, and 4D of the fourth optical system 4 divide the subject image formed on the primary imaging surface 21 into four regions, and divide the subject image in each region into the second region. The four image pickup devices 41A, 41B, 41C and 41D constituting the image pickup means 41 are imaged respectively.

Generally, for focusing in an image pickup apparatus such as a small video camera or a still video camera, at least a part of lenses constituting an image pickup element or a lens system is reciprocally moved in the optical axis direction, and at this time, a high frequency component of a video signal. The so-called TV AF system is used to detect the output peak of the.

However, in the image pickup apparatus of this type, even at the time of image pickup, the image pickup element or a part of the lens of the lens system is reciprocally driven in the optical axis direction, so that a high-definition image is deteriorated due to vibration or the like. There is a problem.

Therefore, the image pickup apparatus in this embodiment is the third one.
The focus state is detected using a signal from the first image pickup means 31 corresponding to the optical system 3, and when the focus adjustment is required, the drive means 33 moves the first image pickup means 31 on the optical axis. Or / and at least a part of the lenses of the third optical system 3 is moved on the optical axis, and at this time, the first optical system 1 or A plurality of lens systems 4A, 4 of the fourth optical system 4
Focusing is performed by moving B, 4C and 4D on the optical axis.

This prevents the high-definition composite image obtained by the fourth optical system 4 from being deteriorated by vibration or the like.

Further, in this embodiment, at least a part of the lenses of the third optical system 3 is moved along the optical axis, for example, at a constant speed, so that the three-dimensional shape of the subject is obtained from the distribution of the focal position of the image. Can be recognized, and the synthesized image obtained by the fourth optical system 4 can be held constant during the recognition operation.

When a high-resolution image is required in this embodiment, the image pickup elements 41A and 41B corresponding to the subject image by the fourth optical system 4 consisting of four lens systems 4A, 4B, 4C and 4D, respectively. , 41C, 41D are divided into images to form images, and the four image pickup devices 41A, 41B, 4
The signal processing system (synthesis processing system) uses the image information from 1C and 41D, and at this time, if necessary, the third optical system 3
The first image pickup means 31 formed in 1 above is combined to pick up the entire subject image.

In a normal case where a high-resolution image is not required, the entire image of the subject is formed on the surface of the first image pickup means 31 by the third optical system 3, and the image is picked up. Image information from is used.

As described above, in this embodiment, the image obtained by the third optical system 3 and the fourth optical system 4 are used when a high-resolution image is required and when it is not necessary. It is configured so that the obtained composite image can be arbitrarily selected and output.

In this embodiment, the optical axes of the third optical system 3 and the fourth optical system 4 are arranged so that they do not coincide with each other, and
The subject image formed on the next image forming surface 21 is re-imaged on the corresponding image pickup element surface at a desired degree of overlap and magnification.

Further, in this embodiment, the sum of the plurality of divided images formed by the fourth optical system 4 is configured so as to include the entire area of the subject image formed by the first optical system 1. That is, as will be described later, the adjacent divided images are configured to overlap each other with pixels in the boundary portion, so that no inconvenience occurs in the image boundary portion.

FIG. 3 is an explanatory diagram showing the overlap of the boundary portion when the divided images formed on the four image pickup devices 41A, 41B, 41C and 41D corresponding to the entire area of the subject image are combined.

In the figure, for example, the boundary portion 41E between the pixels of the image pickup element 41A and the image pickup element 41B is the image pickup element 4 of each image pickup element 4A.
By extracting the corresponding pixels included in 1A and 41B when they are combined in the signal processing system, it is possible to continuously output the image of the boundary portion without interruption.

Next, the image processing method of this embodiment will be described with reference to FIG. FIG. 4 is a block diagram of a main part of a signal processing system of the image pickup apparatus of this embodiment.

In this embodiment, for example, when a high resolution image is to be obtained, the image pickup devices 41A and 41A shown in FIG.
The sample and hold circuits (S / H circuits) 51A, 51B, 51C and 51 are provided with the electric signals from 1B, 41C and 41D.
Each sample is held by D, and each analog-digital conversion circuit (A / D conversion circuit) 52A, 52B, 52C, 52D
The analog signal is converted into a digital signal by and stored in each memory (storage circuit) 53A, 53B, 53C, 53D. Then, each memory 53A,
Information is read from 53B, 53C, and 53D and combined by the image combining processing circuit 54 to obtain a high-resolution image.

If necessary, the image from the first image pickup means 31 is sample-held by the sample-hold circuit 55, converted into a digital signal by the A / D conversion circuit 56, and the image stored in the memory 57 is used. I am trying.

On the other hand, in order to obtain a normal image which does not require high resolution, the sample-hold circuit (S / H circuit) 55 samples and holds the electric signal from the image pickup device 31 shown in FIG. -Digital conversion circuit (A /
An analog signal is converted into a digital signal by a D conversion circuit) 56 and stored in a memory (storage circuit) 57. Then, the information is read from the memory 57 and processed by the image processing circuit,
I'm getting a normal image.

In this embodiment, the entire screen of the subject image is divided into four parts, and the respective divided images are combined by the signal processing system (combining processing system) to obtain one high-resolution image. However, the number of pixels can be substantially increased by arbitrarily increasing the number of four lens systems constituting the fourth optical system and the number of image pickup elements corresponding to the lens systems, and thus, a higher resolution image can be obtained. Can be obtained.

Further, in the case of a still image, a higher resolution image can be obtained by using it together with the conventional pixel shifting method described above.

[0053]

According to the present invention, by appropriately configuring each element of the image pickup apparatus as described above, it is possible to obtain a high-resolution image by using the image pickup element having a limited number of pixels, and further, the photographing optical An image that does not cause inconvenience at the boundary between images can be obtained without limiting the back focus of the system, and an output image can be arbitrarily selected depending on whether a high-resolution image is required or not. Can be third
If the information of the image obtained by the optical system is used, the divided images can be combined with high accuracy.

Further, it is possible to achieve an image pickup apparatus capable of obtaining a high-resolution image without causing image deterioration even during automatic focusing.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an optical system according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram related to image composition according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a main part of a signal processing unit according to the first embodiment of the present invention.

[Explanation of symbols]

1 1st optical system 2 2nd optical system 3 3rd optical system 4 4th optical system 21 1st image formation plane 31 1st image pickup means 41 2nd image pickup means 4A, 4B, 4C, 4D lens Systems 41A, 41B, 41C, 41D Image pickup elements 51A, 51B, 51C, 51D Sample hold circuit 55 Sample hold circuits 53A, 53B, 53C, 53D A / D conversion circuit 56 A / D conversion circuits 55A, 55B, 55C, 55D Memory 57 memory 54 image synthesis processing circuit 58 image processing circuit

Claims (7)

(57) [Claims] 1. A second optical system which forms a subject image on a planned image forming plane by the first optical system, and is arranged on the optical axis of the first optical system and near the planned image forming plane. A first image pickup means for all the subject images formed on the planned image forming surface by the third optical system arranged on the optical axis of the first optical system and behind the second optical system. Image formed on the planned image forming plane by the fourth optical system which is re-imaged on the optical axis and has an optical axis outside the optical axis of the first optical system, and which is arranged behind the second optical system. Device for re-imaging a part of the image on the second image pickup means and obtaining high-definition image information by using image information obtained by the first image pickup means and the second image pickup means In addition, by using a signal from the first image pickup means, at least a part of the lenses constituting the third optical system is driven by the driving means, and / or the first image pickup means is moved on the optical axis. Imaging apparatus being characterized in that as possible. 2. The fourth optical system has a plurality of lens systems, and the second image pickup means has a plurality of image pickup devices corresponding to the plurality of lens systems. The image pickup apparatus according to claim 1. 3. The plurality of lens systems of the fourth optical system are provided on respective image pickup element surfaces of object images of respective areas when the object image formed by the first optical system is divided into a plurality of areas. The image pickup apparatus according to claim 2, wherein the image is formed on the image. 4. One piece of image information is obtained by utilizing image information obtained from a plurality of image pickup devices constituting the second image pickup means and image information obtained from the first image pickup means. The imaging device according to claim 2 or 3, characterized in that 5. The image pickup apparatus according to claim 2, wherein the third optical system and the plurality of lens systems of the fourth optical system have different imaging magnifications. 6. A second optical system having the same optical axis as that of the first optical system arranged near the planned image-forming surface by forming a subject image on the planned image-forming surface by the first optical system. The first image pickup means includes all of the subject image formed on the planned image forming plane by the third optical system which is arranged behind the second optical system and whose optical axis is aligned with that of the first optical system. A plurality of areas obtained by dividing the subject image formed on the planned image forming surface while forming an image on the surface.
And the first optical system of the plurality having a different optical axis optical axis lens system have a second optical system by the fourth optical system provided behind said plurality of plurality of corresponding to the lens system An image is formed on each of the plurality of image pickup device surfaces of the second image pickup device having an image pickup device, and image information from the plurality of image pickup devices is combined to obtain image information about the entire subject image. The image pickup device, wherein at least a part of the lenses forming the third optical system is driven by the driving means using the signal from the first image pickup means, and / or the first image pickup means is used as an optical axis. An imaging device characterized in that it can be moved upward. 7. The image pickup apparatus according to claim 6, wherein the plurality of lens systems of the third optical system and the plurality of lens systems of the fourth optical system have different imaging magnifications.